WASHINGTON — Sen. Bernard Sanders, I-Vt., introduced legislation Tuesday to break up banks that have grown so big that the U.S. Justice Department fears the financial system would be put at risk if criminal charges were filed.

Rep. Brad Sherman, D-Calif., proposed a companion bill in the House.

Sanders said the 10 largest banks in the United States are bigger now than before a taxpayer bailout following the 2008 financial crisis.

Attorney General Eric Holder Jr. told the Senate Banking Committee last month that the Justice Department might not pursue criminal cases against big banks because filing charges could “have a negative impact on the national economy, perhaps even the world economy.”

Sanders said, “We have a situation now where Wall Street banks are not only too big to fail, they are too big to jail.”

Sherman added, “They claim; ‘if we go down, the economy is going down with us,’ but by breaking up these institutions long before they face a crisis, we ensure a healthy financial system where medium sized institutions can compete in the free market.”

The Sanders and Sherman legislation would give the Treasury Department 90 days to identify commercial banks, investment banks, hedge funds and insurance companies whose “failure would have a catastrophic effect on the stability of either the financial system or the United States economy without substantial government assistance.”